Audio recordings: Andrew Hsiu. (2017). Laha (Na Tay) audio word list. Zenodo. http://doi.org/10.5281/zenodo.1123351
On a chilly morning in February 13, 2014, I went to Pi Toong commune, Mường La district, Sơn La province, Vietnam and found that there was one isolated Laha village there called Nà Tạy. The name of the village is in Black Thai, where Nà means 'field', and Tạy is a kind of wild edible fruit found in the local forests. Nà Tạy is located in a relatively flat area closer to the river, with higher-quality arable land and rice fields surrounding it. This points to the historically earlier arrival of the Laha, as they were able to secure better farming land than later migrants such as the Black Thai and Hmong.
Another isolated Laha village in Pi Toong commune is located about 25 km away. 2 or 3 Kháng villages (incl. bản Pá Hơp) are located over 40 km away in Nậm Giông commune, on the other side of the Sông Đà river. Most of the houses in the Laha village are on stilts, and the women dress just like that Black Thai (Thai Dam), with topknot hairstyles. The khaen mouth organ of the Black Thai is not played by the Laha in this village. Fortunately, the children still speak Laha. Villagers report that the Laha villages in Mường Bú and Chieng Xom communes, closer to Sơn La City, cannot speak Laha anymore but can still understand some of it.
My informant was Quàng Văn Chiêu (male, born Sept. 26, 1989; completely fluent in Vietnamese, Laha, and Black Thai).
Laha of Noong Lay commune (which Edmondson had researched) preserves final -l and initial Cl-, but Pi Toong does not. However, r- / -r- (initial/medial r; sometimes a retroflex and sometimes an alveolar trill; I think they're in complementary distribution) is very interesting, and may point to retroflexes in Proto-Kra. Noong Lay Laha has d- instead of r-. v- also comes as a surprise, as it is not present in either Noong Lay or Ta Mit Laha.
Laha (Noong Lay) phl- : Laha (Pi Toong) f-
Laha (Noong Lay) pl- : Laha (Pi Toong) ph-
Laha (Noong Lay) bl- : Laha (Pi Toong) v-
Laha (Noong Lay) -l : Laha (Pi Toong) -n
Laha (Noong Lay) kl- : Laha (Pi Toong) k-
Laha (Noong Lay) d- : Laha (Pi Toong) r- [but not always]
Some forms are also more similar to Ta Mit Laha than to Noong Lay Laha. But Pi Toong Laha is obviously the same language as Noong Lay Laha, and my informant could understand Edmondson's recordings of Noong Laha but not Ta Mit Laha.
This is a previously undocumented variety of Laha. Evidently more research needs to be done urgently on different dialects, especially since conservative features of the language such as initial clusters, final -l, etc. may be lost among younger generations as with the Saek language of Nakhon Phanom province, Thailand.
Their autonym was xon⁵⁵xa³⁵, with xon⁵⁵ meaning 'person' in Tai Dam.